1. Field of the Invention
The present invention relates to a method for drawing the distribution area of data points on a coordinate plane and a program for causing a computer to execute the method.
2. Description of the Related Art
Generally, coordinate planes are often used to express relationships between plural data having a pair of variables. Further, the relationships between the plural data having the pair of variables can be digitized by finding regression straight lines and regression curved lines with respect to data groups containing the plural data. For example, Patent Documents 1 through 3 disclose methods for expressing the characteristics of distribution of data points on coordinate planes.
Furthermore, in a case where there is information that classifies data points into layers, the colors and shapes of marks indicating the data points are changed to express the data points on the coordinate planes. Thus, distribution of the data points of the plural layers can be expressed on a single coordinate plane.
As described above, the coordinate planes are suitable for expressing the relationships between the plural data having the pair of variables.
However, if the single coordinate plane displays a large number of the layers and the data points, the marks indicating the data points are overlapped with each other, which results in a difficulty in recognizing the characteristics of the distribution of the data points in the respective layers.
Moreover, without being limited to the coordinate planes on which the plural layers are displayed, small figures per se cause the marks indicating the data points to be reduced in size, which results in a difficulty in recognizing the characteristics of the distribution of the data points.
In order to overcome such difficulties, known methods draw probability ellipses for the respective layers. However, the probability ellipse does not accurately express actual distribution of data points.
Patent Document 1: JP-B2-3639636
Patent Document 2: JP-B2-3944439
Patent Document 3: JP-A-2007-248198
Patent Document 4: JP-B2-3888938